1/3 of the sum of a number and 2 plus 5 is -20 The phrase a number means an arbitrary variable, let's call it x. x the sum of a number and 2: x + 2 1/3 of the sum of a number and 2 1/3(x + 2) 1/3 of the sum of a number and 2 plus 5 1/3(x + 2) + 5 The phrase is means equal to, so we set 1/3(x + 2) + 5 equal to -20: 1/3(x + 2) + 5 = -20